Western Digital Technologies, Inc.

Scott A Ottele

Guoxiao Guo

Charles A Park

Richard Conway

Joey Martin Poss

Yanning Liu

Gary Allan Herbst

Ryan P Mayo

Siri S Weerasooriya

Brian P Rigney

Edgar D Sheh

Soo-Choon Kang

Jason Laks

Example control circuitry, data storage devices, and methods for parallel self-servo writing of interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable independent determination of phase while writing servo patterns in parallel to the two surfaces using their respective heads.

Interleaved servo patterns in a data storage device

Example circuits, data storage devices, and methods to provide parallel self-servo write in a data storage device are described. The data storage device may include multiple heads actuated over respective surfaces of storage media and at least two preamplifiers and read paths to a channel circuit. Control circuitry may select heads connected through different preamplifiers for parallel self-servo write and receive read signals from the selected heads in parallel. These read signals, which may be based on self-servo write reference spirals previously written to the storage media, may be used to determine respective position error signals for the two heads and control their respective positions with corresponding control signals to a shared voice control motor and respective micro and/or milli actuators on the arms supporting the heads.

Parallel self-servo write circuitry in a data storage device

Example storage preamplifier circuits, data storage devices, and methods for parallel self-servo write are described. The data storage device may include a pair of preamplifier circuits electrically connected to respective banks of read heads actuated over a storage media surfaces. In read/write operation, each preamplifier circuit may selectively and sequentially provide read signals from a selected head to a pair of read channel interfaces. In self-servo write operation, each preamplifier circuit may selectively and in parallel provide read signals from a selected head in their corresponding banks of read heads to the pair of read channel interfaces. For example, the pair of read channel interfaces for two-dimensional magnetic recording may receive read signals from one read sensor in a head in the first bank of heads and another read sensor for another head in the second bank of heads.

Preamplifier circuit for parallel self-servo write

Example servo interface circuitry, data storage devices, and methods to provide parallel self-servo write in a data storage device are described. The data storage device may include servo control circuitry that includes at least three digital-analog converters to provide control signals to the voice control motor (VCM) and arm actuators (e.g., micro actuators and milli actuators) of the data storage device. In data read/write mode, one actuator control signal controls the milli actuator for the target arm/head and another actuator control signal controls the micro actuator for the target arm/head. In self-servo write mode, one actuator control signal controls the micro actuator for one target arm/head and the other actuator control signal controls the micro actuator for another target arm/head for parallel self-servo writing.

Servo interface circuitry for parallel self-servo write

Example control circuitry, data storage devices, and methods for parallel self-servo write in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. Position error signals may be determined from each read signal and corresponding position compensation values may be determined for their respective microactuators. Application of these compensation values may maintain their relative positions for parallel writing of servo tracks based on their respective spiral reference patterns and TPI settings.

Parallel self-servo write in a data storage device

Example control circuitry, data storage devices, and methods for determining wedge repeatable runout correction values for interleaved servo patterns in a data storage device are described. The data storage device may include multiple heads actuated over different surfaces of a data storage device and receive read signals from two different heads over two different surfaces in parallel. The servo wedges of the two surfaces may be offset to enable parallel learning of wedge repeatable runout correction values.

Wedge repeatable runout correction for interleaved servo patterns in a data storage device

Example storage medium servo patterns, data storage devices, and methods to provide servo tracks with continuously varying frequency in a data storage device are described. The data storage device may include storage media, such as magnetic disks, having servo sectors that define servo tracks, where adjacent servo tracks have continuously varying frequency as the head moves from one servo track to the next. As the head is actuated over the storage medium, a target track frequency may be determined based on the radial position of a target servo track and the channel frequency may be set to the target track frequency to follow the target servo track.

Continuous frequency servo in a data storage device

A disk drive is disclosed comprising a head actuated over a disk surface, the head comprising a fly height actuator for controlling a fly height of the head, and a ramp for parking the head. A ramp procedure is executed by applying a control signal to the fly height actuator to decrease the fly height and receiving a corresponding fly height signal, and detecting whether the head is on the ramp in response to the fly height signal.

Disk drive detecting when head is on ramp

A disk drive is disclosed comprising a head actuated over a disk, wherein a bootstrap spiral track is written on the disk. While servoing on the bootstrap spiral track at least one circular reference track is written on the disk. A velocity profile is adjusted in response to the circular reference track, and a plurality of spiral tracks are written to the disk in response to the velocity profile.

Disk drive performing in-drive spiral track writing

A disk drive is disclosed comprising a head actuated over a disk, and a spindle motor operable to rotate the disk. A bootstrap spiral track is written to the disk, wherein the bootstrap spiral track comprises a high frequency signal interrupted by sync marks. A first sync mark is written while writing a first part of the bootstrap spiral track, and a second sync mark is written while writing a second part of the bootstrap spiral track. A switch between writing the first sync mark and the second sync mark is made in response to a spindle BEMF voltage, thereby generating a sync mark seam in the bootstrap spiral track.

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Longmont, CO, United States of America

Scott A Ottele